2.3.3 GI Motility and Dysmotility III Flashcards
Increases in what will cause the stomach to switch from rapid emptying to slow emptying?
Viscosity
Particle size
Calories and Osmo
Nutrients can regulate what neuronal input in gastric emptying?
Work via Vagus nerve and enteric nervous system
What are the characteristics of slow emptying?
low fundus tone, narrow pylorus, contracted duodenum and retropulsion is favored
What is the Pylorus state?
when pylorus is open and middle antrum contracts, duodenum does not contract and allow emptying
What is the role of neurotransmitters on the muscle contractions of the stomach?
Required for smooth muscle contractions
What is pyloric stenosis?
Narrowing of the pylorus due to thickening of pylorus
Projectile VOMITING
What is dumping syndrome?
rapid emptying due to surgery, vagotomy, peptic ulcers, cyclic vomiting, drugs
Early and late dumping syndrome
What is phase 1 of the fastering motor pattern? (between meals)
quiescent, little to no contractions
What are the ICC in the stomach?
interstitial cell of Cajal → each other and smooth mm (via gap junctions) and myenteric ganglia (varicosities)
Cells have spontaneous electrical rhythmicity
What is the role of the esophagus in gastric filling?
bolus activates inhibitory enteric nerves via vagus n. to relax LES
How does gastric emptying change between a glucose solution, protein solution, and solid meal?
What is electrogastrography?
detection of slow propagating waves, slow/fast
What is breath testing?
labeled octanoate, appearance of CO2 associated with gastric emptying
(slow appearance = poor emptying)
What are the characteristics of rapid emptying?
high fundus tone
wide pylorus
relaxed duodenum
propulsion is favored
What are some of the mechanisms of delayed gastric emptying?
Abnormal slow waves
Damage to enteric nervous system
Increased resistance: pyloric stenosis and diabetic pylorospasm
What is gastroparesis?
delayed emptying, due to ↓ driving force or pyloric obstruction, common w/ diabetes, sclerosis, surgery
What is scintigraphy?
gamma radiation consumed to generate image over time
What is phase II of the fasting motor pattern?
irregular contractions
Duodenal gastric reflux can be caused by?
Pyloric incompetence
What is barium radiography?
ingestion of radioactive material and XRay taken
What is the basal electrical rhythm associated with ICCs?
ICC cells maintain this rhythm of depolarization due to Ca++ and K+ flux, may not result in mm contraction
Describe terminal antral contraction and grinding
Contractions of terminal antrum forces particles back through, which causes them to break down into smaller sizes
What is the role of the fundus in gastric filling?
efferent nerves tell gastric mm relax for meal
What are the local and vaso-vagal pathways in gastric relaxation?
NO and VIP signal for relaxation
What is the role of the duodenum in gastric filling?
nutrients and bolus activate vagus to inhibit motor neurons
Describe the different phases of the antral pump
What can cause tachygastria?
Abnormal pacemarker which is abnormally fast
What is the role of the pacemaker cell in the stomach?
Pacemaker – located in body (corpus) produces slow propagating waves
What is the difference between propulsion, gastric emptying, and retropulsion?
Propulsion - proximal antrum contracts filling distal antrum
Gastric emptying - middle antrum contracts emptying
Retropulsion - Distal antrum contracts and granding (movement of chyme in oral direction)
What is the function of the proximal portion of the stomach?
accommodation of incoming meal, reservoir, receptive relaxation, tonic contractions
What is diabetic gastroparesis?
Generation of slow waves that may originate from ICC (dysrhythmias)
Pathway for slow wave propagation
Loss of ICC can impair neural imputs
What are the 3 mechanisms that regulate gastric reservoir function?
Stimulation of pharynx and esophagus activates inhibitory enteric nerves via vagus
Can be triggered by distension leading to activation of vagusor enteric neurons
Nutrients or stretch in duodenum or distal gastric regions activate vagal or enteric pathways leading to inhibition of motor neurons
Phase III is important in?
Allows for emptying of the stomach that might have not occured in the normal digestive phase
What are the properties of the slow waves of the stomach?
propagate quickly across stomach and slowly down the stomach
What is the sieving function of the stomach?
smaller particles on top exit during emptying when middle antrum contracts
What is phase III of the fasting motor pattern?
regular contractions, open pylorus
What are some causes of increased gastric emptying?
Decreased fundic compliance
Loss of pyloric resistance
Failure of duodenal feedback
What is the function of the distal portion of the stomach?
pump, mixing and grinding, phasic contractions
